Instanton corrections and Emergent Strings Baume, Florent; Marchesano, Fernando; Wiesner, Max
The journal of high energy physics,
04/2020, Letnik:
2020, Številka:
4
Journal Article
Recenzirano
Odprti dostop
A
bstract
We study limits of infinite distance in the moduli space of 4d
N
= 2 string compactifications, in which instanton effects dominate. We first consider trajectories in the hypermultiplet ...moduli space of type IIB Calabi-Yau compactifications. We observe a correspondence between towers of D-brane instantons and D-brane 4d strings, such that the lighter the string the more relevant the instanton effects are. The dominant instantons modify the classical trajectory such that the lightest D-brane string becomes tensionless even faster, while the other strings are prevented to go below the fundamental string tension. This lightest string is dual to a fundamental type IIB string and realises the Emergent String Conjecture. We also consider the vector multiplet moduli space of type I string theory on
K
3
×
T
2
, where quantum corrections can also become significant. Naively, we only find trajectories that correspond to decompactification limits, in apparent contradiction with the picture obtained in some dual setup.
A
bstract
We compute the flux-induced F-term potential in 4d F-theory compactifications at large complex structure. In this regime, each complex structure field splits as an axionic field plus its ...saxionic partner, and the classical F-term potential takes the form
V
=
Z
AB
ρ
A
ρ
B
up to exponentially-suppressed terms, with
ρ
depending on the fluxes and axions and
Z
on the saxions. We provide explicit, general expressions for
Z
and
ρ
, and from there analyse the set of flux vacua for an arbitrary number of fields. We identify two families of vacua with all complex structure fields fixed and a flux contribution to the tad- pole
N
flux
which is bounded. In the first and most generic one, the saxion vevs are bounded from above by a power of
N
flux
. In the second their vevs may be unbounded and
N
flux
is a product of two arbitrary integers, unlike what is claimed by the Tadpole Conjecture. We specialise to type IIB orientifolds, where both families of vacua are present, and link our analysis with previous results in the literature. We illustrate our findings with several examples.
Instantons and infinite distances Marchesano, Fernando; Wiesner, Max
The journal of high energy physics,
08/2019, Letnik:
2019, Številka:
8
Journal Article
Recenzirano
Odprti dostop
A
bstract
We consider geodesics of infinite length and with constant 4d dilaton in the (classical) hypermultiplet moduli space of type II Calabi-Yau compactifications. When approaching such infinite ...distance points, a large amount of D-instantons develop an exponentially suppressed action, substantially modifying the moduli space metric. We consider a particular large volume/strong coupling trajectory for which, in the corrected metric, the path length becomes finite. The instanton effects also modify the cllassical 4d dilaton such that, in order to keep the 4d Planck mass finite, the string scale has to be lowered. Our results can be related, via the c-map, to the physics around points of infinite distance in the vector multiplet moduli space where the Swampland Distance Conjecture and the Emergence Proposal have been discussed, and provide further evidence for them.
The EFT stringy viewpoint on large distances Lanza, Stefano; Marchesano, Fernando; Martucci, Luca ...
The journal of high energy physics,
09/2021, Letnik:
2021, Številka:
9
Journal Article
Recenzirano
Odprti dostop
A
bstract
We observe a direct relation between the existence of fundamental axionic strings, dubbed EFT strings, and infinite distance limits in 4d
N
= 1 EFTs coupled to gravity. The backreaction of ...EFT strings can be interpreted as RG flow of their couplings, and allows one to probe different regimes within the field space of the theory. We propose that any 4d EFT infinite distance limit can be realised as an EFT string flow. We show that along such limits the EFT string becomes asymptotically tensionless, and so the EFT eventually breaks down. This provides an upper bound for the maximal field range of an EFT with a finite cut-off, and reproduces the Swampland Distance Conjecture from a bottom-up perspective. Even if there are typically other towers of particles becoming light, we propose that the mass of the leading tower scales as
m
2
∼
T
w
in Planck units, with
T
the EFT string tension and
w
a positive integer. Our results hold even in the presence of a non-trivial potential, as long as its energy scale remains well below the cut-off. We check both proposals for large classes of 4d
N
= 1 string compactifications, finding that only the values
w
= 1
,
2
,
3 are realised.
A
bstract
Swampland criteria like the Weak Gravity Conjecture should not only apply to particles, but also to other lower-codimension charged objects in 4d EFTs like strings and membranes. However, ...the description of the latter is in general subtle due to their large backreaction effects. In the context of 4d
N
= 1 EFTs, we consider
1
2
BPS strings and membranes which are fundamental, in the sense that they cannot be resolved within the EFT regime. We argue that, if interpreted from the EFT viewpoint, the 4d backreaction of these objects translates into a classical RG flow of their couplings. Constraints on the UV charges and tensions get then translated to constraints on the axionic kinetic terms and scalar potential of the EFT. This uncovers new relations among the Swampland Conjectures, which become interconnected by the physical properties of low-codimension objects. In particular, using that string RG flows describe infinite field distance limits, we show that the WGC for strings implies the Swampland Distance Conjecture. Similarly, WGC-saturating membranes generate a scalar potential satisfying the de Sitter Conjecture.
A landscape of AdS flux vacua Marchesano, Fernando; Quirant, Joan
The journal of high energy physics,
12/2019, Letnik:
2019, Številka:
12
Journal Article
Recenzirano
Odprti dostop
A
bstract
We analyse type IIA Calabi-Yau orientifolds with background fluxes and D6- branes. Rewriting the F-term scalar potential as a bilinear in flux-axion polynomials yields a more efficient ...description of the Landscape of flux vacua, as they are invariant under the discrete shift symmetries of the 4d effective theory. In particular, expressing the extremisa tion conditions of the scalar potential in terms of such polynomials allows for a systematic search of vacua. We classify families of = 0 Minkowski,
N
= 1 AdS and
N
= 0 AdS flux vacua, extending previous
N
findings in the literature to the Calabi-Yau context. We compute the spectrum of flux-induced masses for some of them and show that they are perturbatively stable, and in particular find a branch of
N
= 0 AdS vacua where tachyons are absent. Finally, we extend this Landscape to the open string sector by including mobile D6-branes and their fluxes.
EFT strings and emergence Marchesano, Fernando; Melotti, Luca
The journal of high energy physics,
02/2023, Letnik:
2023, Številka:
2
Journal Article
Recenzirano
Odprti dostop
A
bstract
We revisit the Emergence Proposal in 4d
N
= 2 vector multiplet sectors that arise from type II string Calabi-Yau compactifications, with emphasis on the role of axionic fundamental strings, ...or EFT strings. We focus on large-volume type IIA compactifications, where EFT strings arise from NS5-branes wrapping internal four-cycles, and consider a set of infinite-distance moduli-space limits that can be classified in terms of a scaling weight
w
= 1
,
2
,
3. It has been shown before how one-loop threshold effects of an infinite tower of BPS particles made up of D2/D0-branes generate the asymptotic behaviour of the gauge kinetic functions along limits with
w
= 3. We extend this result to
w
= 2 limits, by taking into account D2-brane multi-wrapping numbers. In
w
= 1 limits the leading tower involves EFT string oscillations, and one can reproduce the behaviour of both weakly and strongly-coupled U(1)’s independently on whether the EFT string is critical or not, by assuming that charged modes dominate the light spectrum.
On supersymmetric AdS4 orientifold vacua Marchesano, Fernando; Palti, Eran; Quirant, Joan ...
The journal of high energy physics,
08/2020, Letnik:
2020, Številka:
8
Journal Article
Recenzirano
Odprti dostop
A
bstract
In this work we study ten-dimensional solutions to type IIA string theory of the form AdS
4
×
X
6
which contain orientifold planes and preserve
N
= 1 supersymmetry. In particular, we ...consider solutions which exhibit some key features of the four-dimensional DGKT proposal for compactifications on Calabi-Yau manifolds with fluxes, and in this sense may be considered their ten-dimensional uplifts. We focus on the supersymmetry equations and Bianchi identities, and find solutions to these that are valid at the two-derivative level and at first order in an expansion parameter which is related to the AdS cosmological constant. This family of solutions is such that the background metric is deformed from the Ricci-flat one to one exhibiting SU(3) × SU(3)-structure, and dilaton gradients and warp factors are induced.
4d strings at strong coupling Marchesano, Fernando; Wiesner, Max
The journal of high energy physics,
1/8, Letnik:
2022, Številka:
8
Journal Article
Recenzirano
Odprti dostop
A
bstract
Weakly coupled regions of 4d EFTs coupled to gravity are particularly suitable to describe the backreaction of BPS fundamental axionic strings, dubbed EFT strings, in a local patch of ...spacetime around their core. We study the extension of these local solutions to global ones, which implies probing regions of strong coupling and provides an estimate of the EFT string tension therein. We conjecture that for the EFT string charge generators such a global extension is always possible and yields a sub-Planckian tension. We substantiate this claim by analysing global solutions of 4d strings made up from NS5-branes wrapping Calabi-Yau threefold divisors in either type IIA or heterotic string theory. We argue that in this case the global, non-perturbative data of the backreaction can be simply encoded in terms of a GLSM describing the compactification, as we demonstrate in explicit examples.
Systematics of type IIA moduli stabilisation Marchesano, Fernando; Prieto, David; Quirant, Joan ...
The journal of high energy physics,
11/2020, Letnik:
2020, Številka:
11
Journal Article
Recenzirano
Odprti dostop
A
bstract
We analyse the flux-induced scalar potential for type IIA orientifolds in the presence of
p
-form, geometric and non-geometric fluxes. Just like in the Calabi-Yau case, the potential ...presents a bilinear structure, with a factorised dependence on axions and saxions. This feature allows one to perform a systematic search for vacua, which we implement for the case of geometric backgrounds. Guided by stability criteria, we consider configurations with a particular on-shell F-term pattern, and show that no de Sitter extrema are allowed for them. We classify branches of supersymmetric and non-supersymmetric vacua, and argue that the latter are perturbatively stable for a large subset of them. Our solutions reproduce and generalise previous results in the literature, obtained either from the 4d or 10d viewpoint.
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